Method of making light weight blocks



Patented Oct. 31, 1933 PATENT OFFICE METHOD OF MAKING LIGHT WEIGHTBLOCKS Erik g ittgni ann Berlin-wilmersdorf, and Wolfgang' Qim 17Claims.

Our invention relates to building material and particularly toheat-insulating light weight blocks with a good mechanical strength.

Light weight and heat-insulating building blocks have previously beenmade of naturally microporous materials which were mixed with 'gas orfoam-producing substances before shaping the blocks, or by the inclusionof readily combustible materials. We have improved the prior methods byproviding a process which produces a finished product having a very lowunit weight, a high heat-insulating characteristic and good mechanicalstrength.

In practicing our invention we finely pulverize any one of a number ofdifferent siliceous materials which may be calcined, and mix mr's fely pverized substance W1 2. calcareous material, which is to act as a cemenor in er in predetermined relative proportions with a sufi'icientquantity of water to form a slurry or a plastic mass, form the same topredetermined shapes,

indurate the formed shapes preferably with steam which may be underpressure and then remove the water therefrom by drying. Preferably thecalcareous material too is pulverized finely before forming the mixture.

The siliceous raw materials which we may use include all of thosesiliceous materials which possess the ability to combine with hydratedlime when subjected to heat, for example steam under pressure. Asexamples of such materials we may mention here the following:sand, cladiatomaceous earth, shale, n 1 a r l, Moler, ram e, sea slime, acid orbasic 5 3g, artificial or natur l pozzuolans WHICH nclude calcinedsllales, cinders, or e 1 We do not desire to specifically His- 3ft'inguish between these materials as their availability, first cost,and cost of preparation as well as ease of grinding or mixing, must beconsidered in each particular case.

As examples of the binder following calcareous materials may bementioned: uick lime, dr or wet slacked lime hydraulic lime, na uralcement, Fortland cement, Roman cement, or the like.

It s one o e essential conditions in our process that the siliceousmaterials and preferably the i high degree of fineness in order toprovide a highly microporous structure in the final product. As notedabove we have found it desirable in certain materials to aid thepulverization thereof by calcining the materials pgiorethey aregulverized.

The relative proportions of the ingr'e ien 5 may be varied within widelimits, if care be taken that 57 the amount of uncombined lime in thefinished J erlin-Friedenau, Germany, assigno sfby' firesne assignments,to Frederick 0. Anderegg, Forest Hills Borough, Pa.

No Drawing. Application April 14, 1933, Serial No. 666,159Vg, and inGermany April 15, 1932 product after induration (hardening) thereof)must be kept to a minimum, which minimum is of 3 course preferably azero amount. If sand or gay, t'di'r'iaceous earth are chosen as rawmaterial and mm as a 1n er we generally take about 15 to 9 parts byweight of lime on 100 parts by weight of 1" total solid substances,dependent on the properties desired in the finished products.

The amount of water also depends on the quality of the finishedproducts. The higher the amount 6 of water is, the lighter blocks,plates, and the like are obtained. If for example 1000 kg. of water areused on 400 kg. of solid substances the finished product has a specificweight of about 0.4; when using, however, 1000 kg. of water on 700 kg.of solid substances the specific weight will be about 0.7. The object ofthe fine pulverization of the raw materials and of the thoroughly mixingoperation is to obtain a mixture which is as homogenous as is possible,and in which the calcareous material may be combined totally. It ispossible to use any one of several different known methods forpulverization, in accordance with the materials being operated on. Aplastic clay for example will readily mix to a slurry when stirredenergetically with the desired amount of water 4 and calcareousmaterials.

Without Timiting the invention thereto, it will i be preferable,however, to finely pulveriz e the raw j materials, independent 0 en na"aii'd strucii ture (granite, sand, diatomaceous earth and so l, on),iffa'ball mill-and to apply the wet process, it the more as waterisnecessary in the course of ii the process. The duration of the millingoper- 0 ation depends upon the nature of the raw ma- 1? terials.Preferably the calcareous materials are added a short time before theground siliceous materials are removed from the mill; in this way thecalcareous materials not only are finely pulverized too but also a verythorough mixture of siliceous and calcareous materials issues from themill. If the raw materials are very hard and coarse it is preferred topass them separate through a mill before mixing and milling themtogether with the other material binder shall be pulverized orcomminuted to a If siliceous materials with a natural H1115-structll'felar'usefi as for example a i'atomaceous ear ey must betreated so long that their germs structure is substantially or whollyde- 105 s roye o 'erwise the mechanical strength? t'fi'i'inishedproducts would decrease materially.

It is necessary, in order to obtain the result desired by us, that theslurry prepared from the finely pulverized raw ma s and an excess of 1water be of such consistency that any harmful segregation beforehardening shall be prevented. It is obvious, that such consistencycannot be readily obtained with lean materials which are 5 lacking incolloids, or if an especially large excess of water is used to secure anexceptionally thin mixture, which will of course have a very lowviscosity. Where the viscosity of the slurry is too low, it may beincreased by causing it to partly l thicken beforefurther operationthereon. Thus the in mixture may be allowed tostand for some time, or itmay be st red for a certain 'l'i'i gth of time, or the mixture may beheated, whereby a chemical reaction between the components can beeffectemside-of-arr autocgve io ijgr m a calcium hydrosilicate'gel'. Theoriginally thin slurry thickens and reharde following the appearance ofa 00110153.! phase? The hereinbefore mentioned calcination of certain ofthe siliceous raw materials has been found advantageous in this step ofour process, as we have found that such calcineg raw materialsaccelerate the prehardenmg o the mix ure, an whaifl'ufth'r fdifid thatit increases the mechanical strength of the finished product. It is ouropinion that this calcining increases the reactivity of those materialswhich are treated in is way.

We have mentioned above that the mixture of finely pulverized rawmaterials can be heated, and in connection with this step of our process,we have found that a prehardening of the mixture by treating it withstea Amder ressure or with a supersaturated steam, until a plastic orspreada6le"'cons1'stency 1's obtained is very valuable. When the mixtureis subjected to steam pressure in an autoclave it thickens or hardensand this action is the result of the formation of a calciumhydrosilicate gel which exhibits the phenomenon tr thixoti'o" hism vanage may be taken of this thixotrophic property of such a mixture toprolong the prehardening until quite a stiff or crumbly consistency isobtained. When this relatively stiff or hard mixture is stirred orbeaten mechanically as in a pug mill or similar apparatus, it revertsinto a softer mass or mixture, which can be more easily formed.

The slurry hereinbefore described may be @further stabilized and themechanical strength of the final product may be increased by theinclusion of a small amount 0W such as asbestos fibers, the amoun eingon the order of several per cent.

The mixture prepared as hereinbefore described is poured into forms ofthe desired dimensions and shape or the prehardened plastic mix is minto the desired shapes either manually or'in relatively simple andinexpensive forms. The molded shapes are then hardened in an auto;-

for a length of time which may extend up to eight hours under steamwhich may reach 399 po cinds. We have found that during this final heaing of the mixture in an autoclave the siliceous material and its binderform a stable skeleton of very fine structure which skeleton structuremay be described as a three-dimensional network. This skeleton, holdsthe excess water othef than that lost during induration. "The qshapssateh aibqyayabl ried t e 'by'artificial or by natural drying, to rige gut all 5 th w ir.-.. 9t changer-il s remain thereby utavmgamic'm omsstructure ofliigh heatwhich was eased originally t 0 t5 e rawmatfji'ials, 4

insulating value, of low unit weight, and of a mechanical strength neverbefore secured.

Thus to give an indication of the lightness of a structure resultingfrom the use of our hereinbefore described process, we have been able tomake blocks having a weight of 10 to 60 pounds per cubic foot, theblocks having a compressive strength of from 500 to 3,500 pounds persquare inch. We do not, however, wish to be limited to these values asit may easily be possible to still further reduce the unit weight and toincrease the compressive strength or blocks made in accordance with ourimproved process.

While we have set forth our improved process in detail and haveparticularly characterized the resulting product, we desire it to beunderstood that the claims cover all equivalents and are to be limitedonly by the prior art.

What we claim is:-

1. A method of making light weight heat-insulating blocks, comprisingthe steps of finely pulverizing a siliceous material and a calcareousbinder, intimately mixing the same with water to a fluid consistency,prehardening said mixture, forming it into desired shapes, completelyhardening said shapes and removing all water therefrom by drying.

2. A method of making light weight blocks of siliceous material and acalcareous binder, including the steps of finely pulverizing the rawmaterials, intimately mixing the pulverized siliceous material and thebinder with water, subjecting the mixture to external conditions foreffecting a chemical reaction therebetween, forming said mixture intodesired shapes, hardening 110 said formed shapes and removing the excesswater therefrom by drying.

3. A method of making light weight blocks, which includes the steps ofseparately finely pulverizing a siliceous material and a calcareous 115binder, intimately mixing said pulverized ma.- terials with an excess ofwater to form a slurry, subjecting the slurry to selected externalconditions for effecting a chemical reaction between the constituents,forming said mixture to produce blocks of predetermined shapes,hardening said shapes under pressure and at a temperature above roomtemperature and then drying out the excess water.

4. A method of making light weight blocks of 125 siliceous material anda calcareous binder, which includes the steps of finely pulverizing theraw materials, intimately mixing them with an excess of water to make arelatively thin slurry, subjecting said slurry to predetermined externalconditions to cause a chemical reaction between the constituents until apredetermined increase in the thickness of the slurry has been efiected,forming said mixture into desired shapes, hardening said shapes atelevated temperature and pressure 135 and then removing the waterremaining in the hardened shapes by drying.

5. A method of making light weight blocks of siliceous material and acalcareous binder, which includes the steps, of finely pulverizing thesaid 1 raw materials, intimately mixing them with an excess of water tomake a relatively thin slurry and in such proportion that the finishedproduct will contain no chemically uncombined binder, subjecting saidslurry to predetermined external 145 conditions to cause a chemicalreaction between the constituents until a predetermined increase in thethickness of the slurry has been effected, forming said mixture intodesired shapes, hardening said shapes by subjecting them to elevated 150COMPOSITIONS, E aminer COATING 0R PLASTIC.

pressure and temperature and then removing the water remaining in thehardened shapes by drying.

6. A method of making light weight blocks having heat-insulatingcharacteristics, which includes the steps of separately finelypulverizing a siliceous material and a calcareous binder, mixing thepulverized raw materials by adding the calcareous binder in from fifteenparts to fifty-five parts by weight to from eighty-five parts toforty-five parts by weight of the siliceous material and mixing thiswith water to form a relatively thin slurry, subjecting said slurry topredetermined external conditions to cause a chemical reaction to takeplace between the constituents thereof until a predetermined increase inthe thickness of the slurry has been effected, forming the thickenedslurry into desired shapes, hardening said shapes by subjecting them tosimultaneous heat and pressure and then drying them to remove all freewater.

up to three hundred pounds in a closed vessel and then drying saidshapes to remove all excess water.

9. A method as set forth in claim 8 in which the siliceous material iscalcined before pulverizing.

10. A method as set forth in claim 8 in which the prehardened mixture isworked mechanically before being formed into the desired shapes.

. 11. A method as set forth in claim 8 in which the prehardening iscaused by subjecting the mixture to steam pressure until it reaches aplastic consistency and then working the mixture mechanically to softenit before forming the same into the desired shapes.

12. A method as set forth in claim 8 in which the chemical reaction andthe prehardening of the mixture are efi'ected by heating the mixtureunder pressure.

13. A method as set forth in claim 8 in which 20 the chemical reactionand the prehardening are 7- A m h d as Se for in l im 6,characteraccelerated by calcining the siliceous material beized by theaddition of a small percentage by fore it is pulverized. weight offibrous material to increase the me- 14. A method as set forth in claim8 in which chanical strength of the final product. the chemical reactionand the prehardening are 25 8. A method of making heat-insulating blockseffected by stirring the mixture.

of low unit weight, which includes the steps of finely pulverizing asiliceous material and a calcareous binder, mixing these materials in aproportion varying from about five times as much siliceous material asof the calcareous binder to about equal amounts, by weight, by addingthe binder to the siliceous material and then mixing this with an excessof water to form a relatively thin slurry, subjecting said slurry topredetermined external conditions to cause a chemical reaction betweenthe constituents of the slurry and predetermined prehardening thereof,forming into the desired shapes, completely hardening said shapes bysubjecting them to steam pressures of 15. A method as set forth in claim8 in which the chemical reaction and the prehardening are effected byletting the mixture stand.

16. A method as set forth in claim 8 in which the mixture of siliceousand calcareous materials and water has added thereto a small percentageof asbestos fibers.

17. A method as set forth in claim 6 in which the siliceous material iscalcined before pulverizing and which includeSthe step of addingasbestos fibers to the slurry to stabilize the same and to increase thestrength of the formed shapes.

ERIK HU'I'IEMANN. WOLFGANG CZERNIN.

